When the battery on the Prius starts to die, what are the signs or symptoms? Or is that something is simply displayed on the display? If it does need to be replaced, and is under warranty, are there any hidden charges? Is there a battery disposal fee, or labor, etc ...

If the battery is still under warranty when it fails then they take care of all the costs. Our gen 1 Prius had to have the battery serviced, and that involved taking it out of the car, cleaning the positive terminals and sealing them, then re-installing the battery. No charge. I doubt they would charge a disposal fee since they collect the battery for in-house recycling.

The battery should last a very long time because it's being kept in it's sweet spot (40%-80%) at all times, no real data on the average failure time exists because there haven't been enough failures at this point since the batteries were first put in vehicles in 1997.

2001 Prius Photos       2005 Prius Photos
1992 Mitsubishi Delica Diesel-WVO Hybrid Photos

The battery is under warranty for 100k miles.

I understand the warranty is 150k in NY & California. Is that true?

if your state has adopted California emissions standards, the extended battery warranty is in place. Check with your dealer or Toyota directly for specific and correct information.

if the battery fails outside of warranty you are most likely going to be liable for its repair. However, the example of the Vancouver, B.C. Prii that are in Taxi service indicates that the battery will last a very long time without any service, both in GenI and Gen II Prii.

Yes, the battery could be very expensive to replace, however if that becomes necessary and the vehicle is still mechanically reliable and drives well, it would be money well spent.

It has been said:
Hybrid drivers come in 3 flavors, greenie, techie and cheapie. Pick any 2.
2005 Prius, Melinium Silver over gray, package 5 (AI)

I've said this before :
1) You have no need to worry about the battery for 8 years (warranty),
2) after that IF a module fails it can be replaced individually
3) There will be LOADS of spare batteries available out of crashed PRII within 8 years, and i would be perfectly happy with a good wokring second hand module
4) In 8 years the volume of batteries produced will be so enormous that it will be almost a commoditty by then, and al ot cheaper than now.

Bottom line : don not worry about the battery.

Why worry so much about the battery.Engines and Transmissions are usually just in warranty until 60,000 miles 5 years.They cost in the $3000-5000 range to repair,and they do fail at under 100,000 miles .Many transmissions have kinda high failure rates-V-6 Honda 5 speeds-many,many,many Dodge trans.
In 100,000 miles I'm going to go thru $1500 in tires(mine only last 30,000,I like good tractions,so change out early).
Most folks won't keep their cars past 100,000 miles.Batteries are simple-the price will go down,but only a tiny percentage of folks here will ever have to buy one.Luck,Charlie